Automatic circuit breaker



Sept. .20, 193 3- vF. M. CHRISTENSEN 2,130,369

AUTOMATIC C IRCUIT BREAKER Filed Sept. 9, 1957 2 Sheets-Sheet l F151F15. 2 F195 2Q LIT/UN ffy. 5 F137. 5

Sept 20, 1938 P. IM. cHRlsTENsEN 2,130,369

lAUTOMATIC CIRCUIT BREAKER Filed Sept. 9, 1937 2 Sheets-SheetI 2 F1377.7 Fly. 5

Patented Sept. 20, 1938 UNITED STATES PATENT OFFICE AUTOMATIC CIRCUITBBEAKEB Company. Hartford, Connecticut Conn., a corporation ofApplication September 9, 1937, Serial No. 163,114

C'laims.

As concerns one of its phases, this invention relates particularly to acircuit breaker of the type disclosed in the patent to Joseph Sachs, No.1,812,843, dated June 30, 1931. In a circuit breaker of this type thereis provided at least one stationary or rupture contact, a movablecontact member carrying at least one movable contact adapted to engagethe rupture contact, an actuator movably connected with the contactmember, an electro-responsive latch bodily movable wth the contactmember and normally connecting it with the actuator for movement inunison therewith, and an operating means, as for instance toggle links,connected with the actuator for moving or holding it and for thus movingor holding the contact member.

As disclosed in the said patent the latch engages directly with theactuator, and it has been heretofore proposed,v in the co-pendingapplication of Joseph Sachs for Automatic circuit break-y er, Serial No.160,249, filed August 2l, 1937, to provide a. modified constructionwherein the latch engages a movable trip member which is separate fromthe actuator but which is normally mechanically connected thereto formovement in unison therewith. This last mentioned construction makes itpossible for the actuator and the latch to be each located in the mostadvantageous relationship to the contact member; and the saidconstruction makes it possible for the major portion of the necessaryforce for moving or holding the contact member to be transmitteddirectly to the contact member independently of the trip member andlatch.

In accordance with the present invention there is provided a separatetrip member as above mentioned, but the parts are so related that thetrip member upon being released by the latch moves only a small distanceand then entirely releases the actuator which moves independently topermit circuit-opening movement of the contact member. By thisarrangement I avoid excessive movement of the trip member and also verygreatly reduce the force transmitted to the latch. Other advantages willappear from the detailed description hereinafter presented.

As concerns another phase of the invention, I do not necessarily limitmysef to a circuit breaker of the type disclosed in the said Sachspatent. In accordance with this phase of the invention the mechanism ofthe circuit breaker is enclosed in a housing comprising two sectionshaving thedivision plane between them parallel with the plane ofmovement of the contact member. The sections preferably constitute thesole guiding (Cl. 2ML-116) and supporting means for the movable parts ofthe circuit breaker, and the said sections are preferably duplicates ofeach other. Further advantages incident to the sectional housing will bepointed out in the detailed description.

In the accompanying drawings a suitable embodiment of the invention isshown, but it will be understood that the drawings are intended forillustrative purposes only and are not to be construed as defining orlimiting the scope of the invention, the claims forming a part of thisspecification being relied upon for that purpose.

Of the drawings:

Fig. 1 is a front view of a circuit breaker embodying the invention, thehandle being in the closed-circuit position.

Fig. 2 is a vertical sectional view taken along the line 2--2 of Fig. 3.

Fig. 3 is a side view oi' the circuit breaker with one section of thehousing removed, the parts being in closed-circuit positions.

Fig. 4 is a bottom view of the circuit breaker partly in section alongline 4 4 of Fig. 1.

Fig. 5 is a horizontal sectional view taken along the line 5 5 of Fig. 3but showing both sections of the housing.

Fig. 6 is a horizontal sectional view taken along the line 6-6 of Fig. 3but showing both sections of the housing.

Fig. 'I is a view similar to Fig. 3 but showing the parts inopen-circuit positions. In this view the mechanism is shown partly insection along a line corresponding to the line 1-1 of Fig. 5.

Figs. 8, 9 and 10 are views similar to Fig. '7 but showing the parts indifferent relative positions.

In describing the circuit breaker as shown in the drawings, I will firstdescribe the principal parts of the circuit breaker mechanism referringonly briefly to the enclosing housing. Thereafter the housing will bedescribed in greater detail. As shown, the housing is made in twosections and serves as the sole means for guiding and supporting thecircuit breaker mechanism.

At least one stationary or rupture contact I is mounted within thehousing near the rear thereof, this contact being carried by a resilientconductor 2. Preferably, and as shown, there is a second stationary orrupture contact 3 carried by a resilient conductor i. The contacts I and3 with their conducting supports are similar to each other and arespaced apart vertically. The contacts I and 3 are substantiallystationary, that is, they are not movable to any substantial extent butonly to the very limited extent permitted by the resiliency of theconductors 2 and l. For

convenience the said contacts I and 3 will be herein designated asrupture contacts.

Mounted within the housing is a contact carrying member 5, which asillustrated comprises two insulating plates 5*, 5EL spaced aparttransversely. Although the invention is not necessarily so limited, thecontact member 5 is shown as being rectilinearly movable forward andrearward.

Extending transversely between the insulating side plates 5, 5a -are twometallic strips or plates 6 and 'I, these having lugs 6, 6e and 1, 7B attheir ends which project through suitable holes in the plates 5H, 5 andare riveted over. Carried by the respective plates 6 and 'I between theside plates 5a, 5a are movable contacts 8 and 9 which are adapted toengage and disengage the respective stationary -or rupture contacts Iand 3.

The contact member 5 is biased for movement in the circuit-opening orcontact disengagin'g direction, that is in the forward direction, and asshown such biasing is effected by means of springs i0, IIJ connectedwith the side plates and positioned adjacent the outer sides thereof.The details of construction and mounting of these springs will be setforth in greater detail hereinafter.

An actuator II is provided which is connected with the contact member 5so as to be movable relatively thereto and so as to be also bodilymovable therewith. The actuator may be variously constructed, but it isshown as being of lever form and as being pivotally connected with thecontact member by means of a transverse pivot pin I2 which extendsthrough openings in the side plates 51, 5a of the contact member.Shoulders of bushings serve to hold the actuator il in its normalcentral position. A coil spring it surrounds one of the shoulders orbushings on the pin I2, and this spring engages the actuator and one ofthe side plates and serves to bias the actuator for movement in theclockwise direction. As hereinafter explained in detail the actuator IIis normally held against movement with respect to the contact member.

A suitable operating means is provided, this means preferably comprisingtwo links or members I4 and I5 pivotally connected with each other atI6. The link or member I4 is formed to also constitute a handle and itis pivotally mounted on the housing for movement about a transverse axisat Il. A portion I4EL of the handle member I4 projects forward and isexposed so as to be conveniently accessible for manual operation. Thelink I5 comprises two separate elements |53, I5 space-d aparttransversely, and separately connected with plates I8, I8 secured to themember I4.

The two elements I 5B, IEE of the link I5 are pivotally connected at I9with the actuator ii. With the parts in the position shown in Fig. 8 thetwo members or links I4 and I5 constitute an overset toggle which holdsthe contact member in its contact engaging or circuit-closing position.Movement of the links I4 and I5 beyond the position shown in Fig. 3 isprevented by the engagement of the handle portion I4a with a shoulder onthe housing.

Movably connected with the contact member 5 is trip member 20, thisbeing mounted upon a transverse pivot pin 2| extending between thesidewalls 5B, 5a of the contact member. The trip member is held inycentral position by suitable shoulders or bushings on the pin 2|.Normally the trip member is held in fixed relationship with the Contactmember and to this end the trip member and the contact member arenormally connected by means of an electro-responsive latch whichispreferably carried by the contact member and which releasably engagesthe trip member.

As concerns the present invention I do not narrowly limit myself as tothe exact character of the electro-responsive latch but I prefer andhave shown-a latch which consists of a bi-metallic thermally responsivestrip 22. This strip carries a transverse latch bar 22HL which normallyengages with the trip member 20. The trip member `is preferably normallypositioned parallel with the side plates 5, 5n and transversely to thedirection of movement of the contact member. The latch 22 is between theside plates and is preferably approximately perpendicular to the tripmember, extending approximately in the direction of movement of thecontact member.

Preferably, but not necessarily, the latch 22 is electrically connectedto form a part of the circuit and to be directly heated by the current.For supporting the latch 22 and for providing electrical connectiontherewith, the transverse plate 6 is formed with an integral extension6b which is offset rearward and which extends downward between the sideplates 5a, 5H. At its lower end the extension 6b has transverse lugs Iicwhich extend through holes in the side plates 5e, 5n to assist inholding the extension 6b in place. The bi-metallic latch 22 has anangularly bent portion 22b which is riveted to the extension 6b. Thisserves not only to mechanically support the latch but also toelectrically connect it with the contact 8. The other end of theb-i-metaliic latch 22 is electrically connected with the transverseplate 1 and with the other movable contact 9 by means of a flexibleconductor 23. As shown; in Fig. 5 the conductor 23 is doubled to provideincreased conducting capacity. Thus with the parts in closed-circuitpositions an electrical connection is established from the contacts land 8 through the conductor 6b, the latch 22 and the conductor 23 to thecontacts 9 and 3.

In order that the bi-metallic latch 22 may be readily adjusted there maybe provided an arm 24 rigidly secured to the latch near the rear thereofand projecting upward. A screw 25 extends forward through av suitablehole in the conductor 6b and has threaded engagement with acorresponding hole in the arm 24. It will be observed that by turningthe screw 25 the latch 22 may be bent or deflected in the clockwisedirection in order to change its operating characteristics.

Preferably there is provided a U-shaped insulating plate 26 whichextends transversely between the main insulating plates 5, 5a, the mainbody of the plate 26 being immediately behind the conductor 6b andsecured thereto by rivets. rEhe plate 26 has a suitable hole therein topei'- mit access to the screw 25. The end portions 25H, 2GE of the plate26 extend forward, being positioned ,respectively below and above thecontacts I, Ii and 3, 9. Adjacent these said end portions are otherinsulating plates 21, 2T, each provided with lugs 21, 2'Ia which projectthrough openings in the main side plates 5a, 51.

The actuator II is suitably connected with the trip member 20 so as tobe held in fixed relationship with the contact member so long as thelatch 22 holds the trip member in fixed relationship.

The connection is such that, when the latch releases the trip member.the actuator is then free to move relatively to the contact memberentirely independently of the trip member. As shown the trip member isprovided with a shoulder 2l* which is normally engaged by an extensionarm II forming a part oi' the actuator I I. 'I'he trip member is furtherprovided with a rearward extending arm 2IIb which is adapted undercertain circumstances, as will be presently explained, to be engaged bythe arm I I.

Preferably, to prevent any possible transverse movement of the actuatorso as to bring the arm III thereof out of cooperative relationship withthe portions 2l) and 20b of the trip member, the link elements I5, I5are provided with extensions I5", I5 which are positioned at the sidesof the arm I IIl to hold it in position.

With the parts in closed-circuit positions, as shown in Fig. 3, themovable contacts are firmly pressed against the rupture contacts, whichhave been moved rearward to a slight extent from their free positions.'I'he overset toggle Il, I5 prevents circuit-opening movement as aresult of the bias of the springs I0, III. The pressure exerted by saidsprings III, III and the pressure exerted on the contacts 8 and 9 by thecontacts I and 3, are transmitted through the link I5 and the operatingmember I4 and serve to normally hold the operating member in itsclosed-circuit position. Inasmuch as the centerline of the link I5extending through the pivotal axes I6 and I9 is below the actuator axisI2, the force transmitted through the link I5 reacts totend to move theactuator I I in the counter-clockwise direction against the bias of thespring I I thus holding the arm II of the actuator against the shoulder20l of the trip member.

The toggle operating means Il, I5 can be manually released by moving theoperating member Il in the counter-clockwise direction sufficiently tobreak the toggle. Thereupon the parts move to the open-circuit positionas shown in Fig. 7 under the influence of the springs I0, III.

As already stated, the latch 22 is responsive to current in the circuit,being preferably connected electrically to form a part of the circuit.Upon the attainment of excess current conditions in the circuit thebi-metallic latch is heated by reason of the current therein, and it isdeflected downward so that the latch bar 22* is disengaged from the tripmember 20. It the operating member is manually held in closed-circuitposition, as shown in Fig. 8, the trip member will move forward to theposition shown in the said figure as soon as released by the latch. Thisforward movement of the trip member occurs as they result of thepressure exerted by the arm IIB against the shoulder 20". As soon as thetrip member has moved sufiiciently to disengage the shoulder 20* fromthe arm II, the actuator moves in the counterclockwise direction, and atthe same time the contact member moves in the forward direction, thesemovements being caused by the springs I0, I Il which overcome the springI3. As the result of this movement the parts reach the relativepositions shown in Fig. 9, the movable contacts being separated from thestationary contacts and the circuit being broken at two places.

With the contact member in its extreme forward position as shown in Fig.9, the springs I0, I are no longer effective and the spring Il tends tomove the actuator I I in the clockwise direction. However, so long asthe handle is held in closedcircuit position such movement of theactuator is prevented by the link I5. with the parts in closed-circuitpositions as shown in Fig. 3, the centerline oi' the link I5 extendingthrough the pivotal axes I and Il, is below the pivotal axis II of theoperating member. However, when the parts shift to the relativepositions shown in Fig. 9 the said centerline of the link I5 is abovethe pivotal axis at I1. Therefore upon release of the handle oroperating member the actuator II is moved in the clockwise direction bythe spring I3 and at the same time the link I5 moves the operatingmember in the counter-clockwise direction to the open-circuit position.

When the actuator nears the end of its movement in the clockwisedirection, the arm IIl thereof engages the arm 20h on the trip member,as shown in Fig. 10, and moves the trip member in the counter-clockwisedirection to restore it to latching relationship with the latch 22. Thisbrings the shoulder 20l on the trip member into engaging relationshipwith the arm IIa of the actuator, as shown in Fig. '7, and all of theparts are in the proper relationship for effecting reclosing of thecircuit breaker, assuming of course that the latch has cooled sufcientlyto engage the trip member.

The operation has been described upon the assumption that the handle isfirst held and then released. It will, of course, be understood thatsuch holding does not ordinarily occur and that the parts moveautomatically and in succession to the positions shown in Figs. 8, 10and 7, without assuming the relationship shown in Fig. 9.

From the drawings and from the foregoing description it will be apparentthat by providing for movement of the actuator entirely independently ofthe trip member, I avoid any large or extensive or excessive movement ofthe trip member, while nevertheless permitting the necessarily extensivemovement of the actuator. It will further be apparent that a very largeportion of the pressure, stress or force necessary to move and hold theContact member is transmitted directly from the actuator to the contactmember. The relationship of the parts is such that the force transmittedto the shoulder 20a is only a small portion of the total forcetransmitted through the link I5; and the force transmitted from the tripmember to the latch 22 is only a very small portion of the pressureexerted against the-shoulder 20a. By reason of this double reduction theforce transmitted to the latch is very small, and it therefore followsthat the latch is substantially free to deflect in accordance withtemperature conditions Without being unduly hampered or retarded byfriction exerted unon it by the trip member.

In the foregoing description I have referred only briefly to theenclosing casing or housing, as this may be widely varied so far as themechanism of the circuit breaker is concerned. However, in accordancewith one phase of the invention I provide a housing which has importantadvantages, particularly when used with o. circuit breakerof the typewhich has been described.

The housing which I prefer and which I have shown is 'of insulatingmaterial, and the said housing comprises two sections 28, 28 whichenclose all of the essential circuit breaker parts and which serve asthe sole supporting and guiding means for these parts. While I do notnecessarily so limit myself, the two circuit breaker sections arepreferably duplicates of each other thus reducing the cost ofmanufacture and providing other important advantages. These two sectionsare assembled in relatively reversed positions but their construction isor may be identical in all respects. The housing sections are connectedwith each other by means of screws at 29, 29 and 30, 30; and they may bemounted on a rear supporting wall by means of screws inserted in theholes 3I, 3|. The housings are narrow and have flat side faces so that aplurality of them may be arranged in closely banked relationship.

Each of the housing sections 28 is provided with a main central recess32 which is rectangular, the said recesses in the two sectionsregistering with each other to form a chamber which is substantiallyclosed at all sides and which receives and encloses most of themechanism of the circuit breaker. The recesses 32, 32 are of such lengththat the ends thereof have direct guiding engagement with the ends ofthe side plates 5a, 5t1 of the contact member; and the recesses are ofsuch width that the sides thereof have direct guiding engagement withthe sides of the said plates 59, 5a. The sidesof the recess preferablyhave suitable clearance grooves 32a, 32EL and 32b therein as clearlyshown in Fig. 2. I'he grooves 32B, 32L provide clearance for the ends ofthe pivot pin 2| and for the lugs 6a, 'Ia and 21e; and the groove 32bprovides clearance for the ends of the pivot pin I2 and for the lugs 3C,ISC. The front walls or" the recesses serve as stops to limit forwardmovement of the contact member.

The handle member I4 is provided with a pivot pin or trunnion at I1, theends of the trunnion being seated directly in suitable holes formed inthe side walls of the housing sections 28, 28. The housing sections areprovided at the front with arcuate notches 33, 33 which register witheach other to provide a slot through which the handle portion I4L1 ofthe operating member I4 projects. As already stated, the housingsections constitute the sole guiding and supporting means for themovable parts of the circuit breaker. By this I mean that the saidmovable parts are supported and held in proper relationship by reason oftheir direct engagement with the housing parts, there being noadditional or separate frame structure having this function. When thehousing sections are separated the movable parts of the circuit breakerare freely separable there- Afrom and when so separated they are nolonger held in their normal operative relationship; that is with themovable parts of the circuit breaker removed from the housing, thehandle member I4 has no fixed relationship to the Contact member 5 andcan be freely moved in any direction within the limits permitted by theconnecting link I5.

'I'he springs I0, I0 which have already been referred to are preferablyat zigzag springs which are positioned in the shallow grooves 321, 32balready referred to. These springs are provided at their upper ends withhooks Ilia, I which engage annular grooves in the trunnion I1 for theoperating member.

In addition to the screws 29, 29 and 30, 3IIA for connecting the housingsections, I preferably provide two metallic transverse connectingelements located respectively near the top and bottom of the housing.These two transverse connecting elements may be formed integrally withvthe before mentioned conductors 2 and 4 and they are so shown, beingdesignated asy 2a and 4a. The transverse member 2Ja is connected withthe housing sections by means of screws 34, 34 and the transverse member4* is connected with the housing sections by means of screws 35, 35.Carried by the transverse connecting elements 2* and 4* are suitablewire connectors or terminals 36 and 31.

Formed in the inner faces of the two housing sections are registeringgrooves forming at least one arcing vent adjacent each arcing zone.Preferably a plurality of such vents are provided adjacent each arcingzone, these being indicated at 38, 38 and 39, 39. These ventscommunicate with the exterior of the housing and preferably suchcommunication is eiected through other registering grooves 40 and 4Iwhich form tortuous passageways. By referring particularly to Fig. 9 itwill be observed that any gases formed .from arcs resulting fromseparation of the contacts are entirely enclosed Within the chamber 32and can escape only through the vents 38, 38 and 39, 39 and through thepassageways 40 and 4I. In so escaping the gases are passed over thesurface walls of the vents and passagewaysand are thus cooled so that nollame can pass to the exterior. It will also be observed that theinsuiating plates 26 and 21, 21 prevent the arc formed gases frompassing inward to any considerable extent, thus protecting the latch andthe movable parts of the mechanism from the action of such gases.

In order to prevent the gases from escaping through the openings whichare necessarily provided for the resilient contact supports 2 and 4,movable insulating shields 42 and 43 are provided. These shields haveholes therein through which the supports 2 and 4 extend and which theyclosely t. The shields are seated in shallow grooves 44 and 45 in thetop and bottom walls of the recesses 32. Preferably, as shown in Fig. 5,the grooves 44 and 45 are extended transversely into the side walls ofthe housing sections and the shields extend into these extensions. Thusthe shields are accurately guided for forward and rearward movement inaccordance with the forward and rearward movement of the contactsupports.

What I claim is:

l. An automatic circuit breaker comprising in combination, a rupturecontact, a movable contact member biased in the circuit-openingdirection and including an electric contact engageable witlrthe rupturecontact, an actuator connected with'the contact member for movementbodily therewith and also for movement relative thereto, operating meansengaging the actuator to control it, a separate trip member movablerelatively to the contact member, an electro-responsively controlledlatch normally connecting the contact member and trip member to maintainthem in xed relationship, the said latch serving upon the attainment ofabnormal current conditions in the circuit to release the trip memberfor independent movement, and means normally enabling the trip member tohold the actuator in fixed relationship with the Contact member andserving upon release of the trip member to release the actuator andpermit it to move independently of the trip member thus enabling thecontact i member to move automatically in the circuitopening direction.

2. An automatic circuit breaker comprising in combination, a rupturecontact, a movable contact member biased in the circuit-openingdirection and includingan electric contact engageable with the rupturecontact, an actuator connected with the contactmember for movementbodily therewith and also for movement relative thereto. operating meansengaging the actuator to control it, a separate trip member movablerelatively to the contact member, an electro-responsively controlledlatch normally connecting the contact member and trip member to maintainthem in ilxed relationship, the said latch serving upon the attainmentoi' abnormal current conditions in the circuit to release the tripmember for independent movement, means normally enabling the trip memberto hold the actuator in xed relationship with the contact member andserving upon release of the trip member to release the actuator andpermit it to move independently o1' the trip member, and toggle linksconnected with the actuator to control it and adapted when in oversetrelationship to normally hold the actuator and contact member inclosed-circuit positions, the said links being normally held in theirsaid overset relationship by pressure transmitted from the contactmember and being biased for movement to their open-circuit relationshipwhen such pressure is reduced by reason oi.' the relative movement oithe actuator upon being released from the trip member.

3. An automatic circuit breaker comprising in combination, two rupturecontacts spaced apart, a movable contact member biased in thecircuitopening direction and including two electric contacts engageablewith the respective rupture contacts, an actuator connected with thecontact member for movement bodily therewith and also for movementrelative thereto, operating means engaging the actuator to control it, aseparate trip member movable relatively to the contact member, a bodilymovable bi-metallic latch electrically connected between the movablecontacts and normally mechanically connecting the contact member and theltrip member to maintain them in ilxed relationship,v the said latchserving upon the attainment of abnormal current conditions therein toautomatically deflect so as to release the trip member for independentmovement, andv means normally enabling the trip member to hold theactuator in xed relationship with the contact member and serving uponrelease of the trip member to release the actuator and permit it to moveindependently of the trip member thus enabling the contact member tomove automatically in the circuit-opening direction.

4. An automatic circuit breaker comprising in combination, a rupturecontact, a movable contact member biased in the circuit-openingdirection and including an electric contact engageable with the rupturecontact, an actuator connected with the contact member for movementbodily therewith and also for movement relative thereto, operating meansengaging the actuator to control it, an electro-responsively controlledlatch bodily movable with the contact xnembei` and movable relativelythereto upon the attainment of abnormal current conditions in thecircuit, and a trip member movable relatively to the contact member andnormally directly engaging the actuator to prevent relative movementthereof, the said trip member being normally engaged and held by thelatch and being released upon electro-responsive movement thereof so asto disengage the actuator to permit movement thereof independently ofthe trip member and to thus enable the contact member to moveautomatically in the circuit-opening direction.

5. An automatic circuit breaker comprising in combination, a rupturecontact, a movable contact member biased in the circuit-openingdirection and including an electric contact engageable with the rupturecontact, an actuator connected with the contact member for movementbodily therewith and also for movement relative thereto, operating meansengaging the actuator to control it, an electro-responsively controlledlatch bodily movable with the contact member and movable relativelythereto upon the attainment of abnormal current conditions in thecircuit, and a trip member movable relatively to the contact member andhaving a shoulder with which the actuator normally directly engages toprevent relative movement oi' the latter, the said trip member beingnormally engaged and held by the latch and being released uponelectroresponsive movement thereof so as to disengage its said shoulderfrom the actuator and permit the latter to move independently or thetrip member and to thus enable the contact member to move automaticallyin the circuit-opening direction.

6. An automatic circuit breaker comprising in combination, a rupturecontact, a rectilinearly movable contact member biased in thecircuitopening direction and including an electric contact engageablewith the rupture contact, an actuator connected with the contact memberfor movement bodily therewith and also for relative pivotal movementabout a transverse axis, operating means engaging the actuator tocontrol it, a bi-metallic latch carried by the contact member andextending approximately in the direction of movement thereof, the saidlatch being adapted toautomatically deflect upon the attainment ofabnormal current conditions in the circuit, and a trip member connectedwith contact member for relative pivotal movement about a transverseaxis and having a shoulder with which the actuator normally directlyengages to prevent relative movement of the latter, the said trip memberbeing normally approximately perpendicular to the latch and beingnormally engaged and held thereby and being released upon automaticdeilection of the latch so as to disengage its said shoulder from theactuator and permit the latter to move independently of the trip memberand to thus enable the contact member to move automatically in thecircuit-opening direction.

7. The combination in an automatic circuit breaker, of a rupturecontact, a movable contact member biased in the circuit-openingdirection and including an electric contact engageable with the rupturecontact, an actuator connected with the contact member for movementbodily therewith and also for movement relative thereto, operating meansengaging the actuator to control it, an electro-responsively controlledlatch bodily movable with the contact member and movable relativelythereto upon the attainment of abnormal current conditions in thecircuit, a trip member movable relatively to the contact member andnormally directly engaging the actuator to prevent relative movementthereof, the said trip member being normally engaged and held by thelatch and being released upon electro-responsive movement thereof so asto release the actuator to permit movement thereof independently of thetrip member and to thus enable the contact member to move automaticallyin the circuit-opening direction, and means engageable with the tripmember to restore it tov latching relationship with the latch when therupture contact, an actuator connected with the contact member formovement bodily there-v with and also for movement relative thereto,operating means engaging the actuator to control it, anelectro-responsively controlled latch bodily movable with the contactmember and movable relatively thereto upon the attainment of abnormalcurrent conditions in the circuit, a trip member movable relatively tothe contact member and normally directly engaging the actuator toprevent relative movement thereof, the said trip member being normallyengaged and held by the latch and being released upon electroresponsivemovement thereof so as to release the actuator to permit movementthereof independently of the trip member and to thus enable theV anelectro-responsively controlled latch bodily l movable with the contactmember and movable relatively thereto upon the attainment of abnormalcurrent conditions in the circuit, a trip -f member movable relativelyto the contact member and having a shoulder with which the actuatornormally directly engages to prevent relative movement of the latter,the said trip member being normally engaged and held by the latch andbeing released upon electro-responsive movement thereof so as todisengage its said shoulder from the actuator and permit the latter tomove independently of the trip member and to thus enable the contactmember to move automatically in the circuit-opening direction, togglelinks connected with the actuator to control it and adapted when inoverset relationship to normally hold the actuator and contact member inclosedcircuit positions, the said links being normally held in'theirsaid overset relationship by pressure transmitted from the contactmember and the said links and actuator being biased for movement totheir open-circuit relationship when such pressure is reduced by reasonof the relative movement of the actuator upon being released from thetrip member, and means engageable with the trip member to restore it tolatching relationship with the latch when the links and the actuator andthe contact member are moved to their open-circuit positions.

10. kIn an automatic circuit breaker, the combination of two rupturecontacts, a rectilinearly movable contact member including twotransversely spaced insulating side plates and also including twoseparate electric contacts carried by the side plates and engageablewith the respective rupture contacts, a manually movable operatingmember, mechanism operatively connecting theoperating member with thecontact member and including an element adapted to release the contactmember from the control of the operating member upon the attainment ofabnormal current conditions in the circuit, and two tension springsconnected with the side plates at the outer sides 'thereof for biasingthe contact member in the circuit-opening direction.

1l. In an automatic circuit breaker, thel combination of two rupturecontacts, a rectilinearly movable contact. member including twotransversely spaced insulating side plates and also including twoseparate electric contacts carried by the side plates and engageablewith the respective rupture contacts, a manually movable 'the operatingmember upon the attainment of abnormal current conditions in thecircuit, and two substantially flat zigzag tension springs closelyadjacent the outer surfaces of the side plates and connected with thesaid plates for biasing the contact member in the circuit-openingdirection.

l2. The combination in an automatic circuit breaker, of a rupturecontact, a movable contact member provided with a contact engageablewith the rupture contact, a manually movable operating member, mechanismoperatively connecting the operating member with the contact member andincluding an element adapted to release the contact member from thecontrol of the operating member upon the attainment of abnormal currentconditions in the circuit, and a two-section insulating housingenclosing all of the aforesaid parts other than the manually engageableportion of the operating member and having the division plane betweenthe two sections parallel with the direction of movement of the contactmember, the said housing sections serving as the sole supporting andguiding means for the aforesaid parts and being free from positiveconnection with any substantially movable parts so that when thesections are assembled the said parts are guided and held between themand so that when the sections are separated the said parts are freelyseparable therefrom.

13. The combination in an automatic circuit breaker, of a rupturecontact, a rectilinearly movable contact member provided with a contactengageable with the rupture contact, a manually movable pivotedoperating member, mechanism operatively connecting the operating memberwith the contact member and including an element adapted to release thecontact member from the control of the operating member upon theattainment of abnormal current conditions in the circuit, and atwo-section insulating housing enclosing all of the aforesaid partsother than the manually engageable portion of the operating member andhaving the division plane between the two sections parallel with thedirection of f movement of the contact member, the said housing sectionsserving as the sole means for rectilinearly guiding the contact memberand for pivotally supporting the operating member and the said housingsections being free from positive connection with any substantiallymovable parts so that when the sections are assembled the said parts areguided and held between them and so that when the sections are separatedthe said parts are freely separable therefrom.

14. In an automatic circuit breaker, the combination of two rupturecontacts spaced apart 75 near the rear, a contact member rectilinearlymovable forward and rearward and provided with two contacts engageablewith the respective rupture contacts, a manually movable pivotedoperating member at the front, mechanism operatively connecting theoperating member with the contact member and including an elementadapted to release the contact member from the control of the operatingmember upon the attainment of abnormal current conditions in thecircuit, and an insulating housing enclosing all of the aforesaid partsother than the manually engageable portion of the operating member andcomprising two duplicate sections having the division plane between themparallel with the direction of movement of the contact member, the saidhousing sections serving as the sole supporting and guiding means forthe aforesaid parts and being free from positive connection with anysubstantially movable parts so that when the sections are assembled thesaid parts are held and guided between them and so that when thesections are separated the said parts are freely separable therefrom.

l5. In an automatic circuit breaker, the combination of two rupturecontacts spaced apart near the rear, a contact member rectilinearlymovable forward and rearward and provided with two contacts engageablewith the respective rupture contacts, a manually movable pivotedoperating member at the front, mechanism operatively connecting theoperating member with the contact member and including an elementadapted to release the contact member from the control of the operatingmember upon the attainment of abnormal current conditions in thecircuit, and an insulating housing enclosing all of the aforesaid partsother than the manually engageable portion of the operating member andcomprising two duplicate sections having the division plane between themparallel with the direction of movement of the contact member, the saidhousing sections serving as the sole means for rectilinearly guiding thecontact member and for pivotally supporting the operating member and thesaid sections being free from positive connection with any substantiallymovable parts so that when the sections are assembled the said parts areheld and guided between them and so that when the sections are separatedthe said parts are freely separable therefrom.

16. In an automatic circuit breaker, the combination of two rupturecontacts spaced apart near the rear, a contact member rectilinearlymovable forward and rearward and comprising two flat insulating platesspaced apart transversely and carrying two contacts engageable with therespective rupture contacts, a manually movable pivoted operating memberat the front, mechanism operatively connecting the operating member withthe contact member and including an element adapted to release thecontact member from the control of the operating member upon theattainment of abnormal current conditions in the circuit, and aninsulating housing enclosing all of the aforesaid parts otherv than themanually engageable portion of the operating member and comprising twoduplicate sections having the division plane between them parallel withthe said plates of the contact member, the'said housing sections servingas the sole means for rectilinearly guiding the contact member and forpivotally supporting the operating member and the said sections beingfree from positive connection with any substantially movable parts sothat when the sections are assembled the said parts are held and guidedbetween near the rear, a contact member rectilinearly movable forwardand rearward and provided with two contacts engageable with therespective rupture contacts, a manually movable pivoted operating memberat the front, mechanism operatively connecting the operating member withthe contact member and including an element adapted to release thecontact member from the control of the operating member upon theattainment of abnormal current conditions in the circuit, and aninsulating housing enclosing all of the aforesaid parts other than themanually engageable portion of the operating member and comprising twoduplicate sections having the division plane between them parallel withthe direction of movement of the contact member, the two housingsections having registering grooves therein adjacent the rupturecontacts and constituting arcing vents communicating with the exteriorof the housing.

18. In an automatic circuit breaker, the combination of two rupturecontacts spaced apart near the rear, a contact member rectilinearlymovable forward and rearward and provided with two contacts engageablewith the respective rupture contacts, a manually movable pivotedoperating member at the front, mechanism operatively connecting theoperating member with the contact member and including an elementadapted to release the contact member from the control of the operatingmember upon the attainment of abnormal current conditions in thecircuit, and an insulating housing enclosing al1 of the aforesaid partsother than the manually engageable portion of the operating member andcomprising two duplicate sections having the division plane between themparallel with the direction of movement of the contact member, the twohousing sections having therein at each end a plurality of registeringgrooves forming arcing vents adjacent the corresponding contacts andalso having at each end other registering grooves communicating with thesaid vents and forming tortuous passageways communicating with theexterior of the housing.

19. The combination in an automatic circuit breaker, of two rupturecontacts spaced apart, near the rear, a rectilinearly movable contactmember provided with a contact engageable with the rupture contact, amanually movable operating member, mechanism operatively connecting theoperating member with the contact member and including an elementadapted te release the contact member from the control of the operatingmember upon the attainment of abnormal current conditions in thecircuit, a two-section 'insulating housing enclosing all of theaforesaid parts other than the manually engageable portion of theoperating member and having the division plane between the two sectionsparallel with the direction of movement of the contact member, and twometallic elements carrying the respective rupture contacts and eachhaving its end portions connected to the respective housing sections.

20. The combination in an automatic circuit breaker, of two stationaryrupture contacts spaced apart near the rear, a rectilineariy movablecontact member provided with a contact engageable with the rupturecontact, a manually movable operating member, mechanism operativelyconnecting the operating member with the contact member and including anelement adapted to release the contact member from the control o! theoperating member upon the attainment of abnormal current conditions inthe circuit, a two-section insulating housing enclosing all of theaforesaid parts other than the manually engageable portion of theoperating member and having the division plane between the two sectionsparallel with the direction of movement o! the contact member, the saidhousing sections serving as the sole means for rectilinearly guiding thecontact member and for pivotally supporting the operating member and thesaid sections being free from positive connection with any movable partsso that when the sections are assembled the said parts are guided andheld between them and so that when the sections are separated the saidparts are freely separable therefrom, and two metallic elements carryingthe respective rupture contacts and each having its end portionsconnected to the respective housing sections.

PAUL M. CHRIS'IENSEN.

